Abstract
A
bstract
A measurement of single top-quark production in the s-channel is performed in proton–proton collisions at a centre-of-mass energy of 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. The dataset corresponds to an integrated luminosity of 139 fb
−
1
. The analysis is performed on events with an electron or muon, missing transverse momentum and exactly two
b
-tagged jets in the final state. A discriminant based on matrix element calculations is used to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and
W
-boson production in association with jets. The observed (expected) signal significance over the background-only hypothesis is 3.3 (3.9) standard deviations, and the measured cross-section is
σ
=
8.2
−
2.9
+
3.5
pb, consistent with the Standard Model prediction of
σ
SM
=
10.32
−
0.36
+
0.40
pb.